Signal processing device and signal processing method that decode encoded information

Abstract

According to an embodiment of the present invention provides the signal processing system. In the signal processing device that estimates information data from a reception signal by performing iterative processing between a demodulator that demodulates data of n(>m) bits obtained by modulating data of m bits into m bits and an ECC decoder and carrying out maximum a posteriori probability decoding, the device has a module that calculates an a posteriori value after demodulation by performing calculation of modulation data having a pattern estimated to have a high probability alone as modulation data to be decoded from all patterns of the modulation data to be decoded when effecting calculation of the a posteriori value after demodulation based on an a priori value fed back from the ECC decoder at the time of effecting modulation for a second or subsequent time.

1 . A signal processing device configured to decode encoded information, the device estimating information data from a reception signal for modulation data by iterative processing between a demodulator configured to demodulate data of n bits, where n is a first positive integer larger than a second positive integer m, obtained by modulating data of m bits based on a predetermined modulation rule into m bits and an error correction code (ECC) decoder and carrying out maximum a posteriori (MAP) probability decoding,
 wherein the signal processing device comprises a module configured to calculate an a posteriori value after demodulation by calculating modulation data with a pattern estimated to be highly probable as modulation data to be decoded among all patterns of the modulation data to be decoded in calculation of the a posteriori value after demodulation based on an a priori value from the ECC decoder.   
   
   
       2 . A signal processing device configured to decode encoded information, the device estimating information data from a reception signal for modulation data by performing iterative processing between a demodulator configured to demodulate data of n bits, where n is a first positive integer larger than a second positive integer m, obtained by modulating data of m bits based on a predetermined modulation rule into m bits and an ECC decoder and carrying out maximum a posteriori probability decoding,
 wherein, when performing modulation for a second or subsequent time, the signal processing device comprises:   a reliability output module configured to output reliability of modulation data of all patterns based on an a priori value of ECC data from the ECC decoder to the demodulator;   a data selection module configured to select modulation data of high reliability based on the reliability obtained from the reliability output module; and   an a posteriori value calculator configured to output an a posteriori value of ECC data of m bits from the a priori value of the ECC data from the ECC decoder, an a posteriori value of the ECC data from the ECC decoder, the modulation data of high reliability selected by the data selection module, and a reception signal for the modulation data.   
   
   
       3 . The device of  claim 2 , wherein the reliability calculator is configured to use a first address at which an absolute value of the a priori value of the ECC data is higher than a threshold value as an address of high reliability, to obtain binary ECC data at the first address from the a priori value of the ECC data, and then to calculate reliability of each modulation data from a Hamming distance between ECC data for modulation data at the address of high reliability and the binary ECC data obtained from the a priori value of the ECC data. 
   
   
       4 . The device of  claim 2 , wherein the data selection module is configured to select modulation data whose reliability output from the reliability calculator is higher than a set threshold value alone from the modulation data of all patterns. 
   
   
       5 . The device of  claim 2 , wherein the a posteriori value calculator is configured to sort addresses subject to calculation of the ECC a posteriori value into a first group comprising at least one address at which the ECC a posteriori value is updated and a second group comprising at least one address at which the ECC a posteriori value is not updated, configured to use the a priori value of the ECC data from the ECC decoder and a modulation data selected by the data selection module and to calculate the a posteriori value of the ECC data for the first group, and configured to use the a posteriori value of the ECC data from the ECC decoder for the second group. 
   
   
       6 . The device of  claim 3 , wherein the reliability calculator is configured to determine the threshold value for determining reliability of the a priori value of the ECC data based on noise in a reception signal for the ECC data and a predetermined value of an error rate of the ECC data at the address of high reliability. 
   
   
       7 . The device of  claim 3 , wherein the reliability calculator is configured to prepare a correspondence table between noise in a reception signal for modulation data and noise in the reception signal for the ECC data in advance, and to measure the noise in the reception signal for the modulation data at the time of reproduction, then to calculate the noise in the reception signal for the ECC data from the prepared correspondence table and the measured noise. 
   
   
       8 . The device of  claim 7 , wherein the correspondence table is created from a plurality of types of predetermined noise in a reception signal for predetermined modulation data and noise of ECC data calculated from a posteriori value of the ECC data obtained by demodulating a reception signal for modulation data comprising each predetermined noise. 
   
   
       9 . A signal processing method of decoding encoded information, the method estimating information data from a reception signal for modulation data by performing iterative processing between a demodulator that demodulates data of n bits, where n is a first positive integer larger than a second positive integer m, obtained by modulating data of m bits based on a predetermined modulation rule into m bits and an ECC decoder and carrying out maximum a posteriori probability decoding,
 wherein, when performing modulation for a second or subsequent time, the method comprises:   obtaining reliability of modulation data of all patterns based on an a priori value of ECC data from the ECC decoder to the demodulator;   selecting modulation data of high reliability based on the obtained reliability; and   obtaining an a posteriori value of ECC data of m bits from an a priori value of the ECC data from the ECC decoder, an a posteriori value of the ECC data from the ECC decoder, the selected modulation data of high reliability, and a reception signal for the modulation data.   
   
   
       10 . The method of  claim 9 , further comprising, when calculating the reliability:
 using a first address at which an absolute value of the a priori value of the ECC data is higher than a threshold value as an address of high reliability;   obtaining binary ECC data at the first address from the a priori value of the ECC data; and   calculating reliability of each modulation data from a Hamming distance between ECC data for modulation data at the address of high reliability and the binary ECC data obtained from the a priori value of the ECC data.   
   
   
       11 . The method of  claim 9 , wherein modulation data comprising reliability higher than a set threshold value alone is selected from the modulation data of all patterns when selecting the modulation data of high reliability. 
   
   
       12 . The method of  claim 9 , wherein the calculating the a posteriori value further comprising:
 sorting addresses subject to calculation of the ECC a posteriori value into a first group comprising at least one address at which the ECC a posteriori value is updated and a second group comprising at least one address at which the ECC a posteriori value is not updated;   using the a priori value of the ECC data from the ECC decoder and a modulation data selected by the data selection module in order to calculate the a posteriori value of the ECC data for the first group; and   using the a posteriori value of the ECC data from the ECC decoder for the second group.   
   
   
       13 . The method of  claim 10 , wherein the threshold value for determining reliability of the a priori value of the ECC data is determined based on noise in a reception signal for the ECC data and a predetermined value of an error rate of the ECC data at the address of high reliability, while calculating the reliability.